Fig. 5

EPN3 enhances EGFR stability and signalling activity by inhibiting the EGFR lysosomal degradation pathway. A KEGG enrichment analysis of A549 cells in which EPN3 was silenced compared with the NC group. B Heatmap showing different gene expression levels in the ErbB signalling pathway. C The protein expression level of EGFR in paracancerous tissue (N = normal) and lung cancer tissue (T = tumour). D The protein expression level of EGFR in tumours was detected by Western blotting (n = 3). E The mRNA expression level of EGFR was detected by qPCR (n = 3). F Protein expression levels of EGFR and downstream effector proteins in A549 and H1975 cells with silenced EPN3 or in H1299 cells overexpressing EPN3. G A549-shNC or A549-shEPN3 cells were treated with CHX (10 µg/ml) at the indicated intervals. The protein stability of EGFR was analysed by Western blotting. Quantitative analysis of the EGFR protein half-life (n = 3). H H1975-shNC cells or H1975-shEPN3 cells were treated with CHX (10 µg/ml) at the indicated intervals. The protein stability of EGFR was analysed by Western blotting. Quantitative analysis of the EGFR protein half-life (n = 3). I Control or EPN3-overexpressing H1299 cells were treated with CHX (10 µg/ml) at the indicated intervals. The protein stability of EGFR was analysed by Western blotting. Quantitative analysis of the EGFR protein half-life (n = 3). J The lysosomal inhibitor CQ (50 µM) and the proteasome inhibitor MG132 (10 µM) were added to A549-shNC or A549-shEPN3 cells. The protein expression levels of EGFR and EPN3 were analysed by Western blotting (n = 3). The protein expression levels were normalized to those of β-tubulin in each sample. Data are presented as the mean ± SD. ns indicates not significant, ****P < 0.0001 vs. control group